Franco A A, Martín-García A P, Egea-Corbacho A, Arellano J M, Albendín G, Rodríguez-Barroso R, Quiroga J M, Coello M D
Environmental Technologies Department, University Institute of Marine Research (INMAR), International Campus of Excellence of the Sea (CEI MAR), Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
Environmental Technologies Department, University Institute of Marine Research (INMAR), International Campus of Excellence of the Sea (CEI MAR), Faculty of Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz, Spain.
Environ Pollut. 2023 Jan 15;317:120689. doi: 10.1016/j.envpol.2022.120689. Epub 2022 Nov 23.
Sludge from Wastewater treatment plants (WWTPs) have been determined as a sink of microplastics (MP) removed from wastewater. The aim of this research work has been to evaluate the presence of these pollutants in the sludge of seven WWTPs (five urban and two industrial), located in southern Spain. Samples were collected in the primary, secondary and digested sludge matrixes, MPs were extracted following wet peroxide oxidation and the removal of cellulose, finally the samples were analyzed according to their abundance, size (from 100 μm to 5 mm), shape, colour, and polymer type. Subsequently, the data obtained on the WWTPs were compared, the main difference among the WWTPs and different sample points showed high heterogeneity in terms of abundance of microplastics, due to the differences in the sludge loaded, the processes and the type of sludge. The results from this study established that the most abundant shape was fibers; regarding the size, 100-355 μm fraction was the most abundant, showing that the amount of MPs increased when the size decreased. Regarding the type of polymers, 23 were identified by ATR-FTIR. Further, Acrylate, PE, EAA and PP were the most abundant found polymers. The presence of MPs in the digested sludge varied from 0.02 ± 0.006 MP g DW to 57.18 ± 20.69 MP g DW in the WWTP 6 (food industry) and WWTP 3 (urban city over 212,000 inhabitants), respectively; higher abundance of MPs found in the primary sludge in respect to secondary sludge; in concordance with the removal from wastewater line reported in other studies. The results obtained showed that MPs were widely present in sludge, becoming a sink of these pollutants, estimating that among 8.05 · 10 and 1.77 · 10 MPs · day were loaded to sludge; therefore, these facilities act as a significant source of MPs into agriculture when sludge is used as soil amendment.
污水处理厂（WWTPs）的污泥已被确定为从废水中去除的微塑料（MP）的汇。这项研究工作的目的是评估位于西班牙南部的七家污水处理厂（五家城市污水处理厂和两家工业污水处理厂）污泥中这些污染物的存在情况。在初级、二级和消化污泥基质中采集样本，通过湿式过氧化物氧化和去除纤维素来提取微塑料，最后根据微塑料的丰度、尺寸（100微米至5毫米）、形状、颜色和聚合物类型对样本进行分析。随后，对污水处理厂获得的数据进行比较，污水处理厂和不同采样点之间的主要差异表明，由于污泥负荷、处理工艺和污泥类型的不同，微塑料的丰度存在高度异质性。这项研究的结果表明，最常见的形状是纤维；就尺寸而言，100 - 355微米的部分最为丰富，表明微塑料的数量随着尺寸减小而增加。关于聚合物类型，通过衰减全反射傅里叶变换红外光谱（ATR - FTIR）鉴定出23种。此外，丙烯酸酯、聚乙烯、乙烯 - 丙烯酸共聚物（EAA）和聚丙烯是发现的最丰富的聚合物。在污水处理厂6（食品工业）和污水处理厂3（居民超过21.2万的城市）中，消化污泥中微塑料的存在量分别从0.02±0.006个微塑料/克干重到57.18±20.69个微塑料/克干重不等；初级污泥中微塑料的丰度高于二级污泥；这与其他研究报道的废水中的去除情况一致。获得的结果表明，微塑料广泛存在于污泥中，成为这些污染物的汇，估计每天有8.05×(10^6)至1.77×(10^6)个微塑料进入污泥；因此，当污泥用作土壤改良剂时，这些设施成为农业中微塑料的重要来源。
